Disruption of the antiproliferative TGF-β signaling pathways in human pancreatic cancer cells

Abstract

Resistance to TGF-b1 occurred in pancreatic cancer cells suggesting that inactivation of TGF-b inhibitory signaling pathways may play an important role in human pancreatic cancer. The aim of our study was to determine the presence of alterations in the main putative components of the TGF-b inhibitory signaling pathways (p15, Smad4, Smad2, TGFb-RII, CDC25A). A panel of human carcinomas of the exocrine pancreas orthotopically implanted and perpetuated in nude mice and pancreatic cancer cell lines were studied. p15 gene alterations, mainly homozygous deletions that involved exons 1 and/or 2, were found in the 62.5% (5 of 8) of pancreatic xenografts whereas Smad4 gene aberrations were found in one of eight xenografts and in two of seven cell lines. Additional aberrations in these genes were acquired during in vivo perpetuation and distal dissemination. Paradoxically, TGFb-RII overexpression and a decrease in CDC25A protein levels were found in all tumors and cell lines. In one cell line, resistance to TGFb1 occurred in the absence of alterations in the genes analysed so far. We conclude that all human pancreatic tumor cells analysed herein have non-functional TGF-b pathways. The majority of cells harbor alterations in at least one of the putative components of TGF-b pathways, mainly in p15 and Smad4 genes. These results suggest that inactivation of TGF-b signaling pathways plays an important role in human pancreatic tumorigenesis.

The TGF-β signaling inhibitor Smad7 enhances tumorigenicity in pancreatic cancer

“…Pancreatic cancers often overexpress TbRII (Friess et al, 1993a;Villanueva et al, 1998), under-express TbRI (Baldwin et al, 1996; (2610 6 ) were injected at two sites subcutaneously in athymic nude mice and tumor growth was measured weekly until week 6. Tumor volume was determined by the equation: where l is length, h is height, and w is width of the tumor.…”

“…Values are means+s.e.mean of six tumors/clone Smad7 in pancreatic cancer J Kleeff et al Wagner et al, 1998), and overexpress all 3 TGF-b isoforms and Smad6 (Friess et al, 1993b;Klee et al, 1999). These cancers also exhibit inactivating mutations of the Smad4 and p15 gene Villanueva et al, 1998). In addition, pancreatic cancers express high levels of cyclin D1 (Gansauge et al, 1997;, which may also interfere with TGF-b signaling pathways (Okamoto et al, 1994).…”

GALV expression enhances the therapeutic efficacy of an oncolytic adenovirus by inducing cell fusion and enhancing virus distribution

“…NP9 and NP18 pancreatic tumor cells were established in our laboratory. 40 Human CAF1 were isolated and characterized in our laboratory from hepatic metastases of a human colorectal carcinoma. All cell lines were grown in Dulbecco's modified Eagle's medium supplemented with 5% fetal bovine serum, with exception of CAF1 cells, which were maintained in Dulbecco's modified Eagle's medium-F12 supplemented with 10% fetal bovine serum and BDMITO þ serum extender (Becton Dickinson, Erembodegem, Belgium).…”

Improved systemic antitumor therapy with oncolytic adenoviruses by replacing the fiber shaft HSG-binding domain with RGD

“…NP-9 and NP-18 (pancreatic adenocarcinomas) cell lines were established in our laboratory. 20 All cell lines were maintained in Dulbecco's modified Eagle's medium containing 5% fetal bovine serum at 37 1C, 5% CO 2 .…”